In vivo modification of refractive power of an intraocular lens implant

ABSTRACT

A change is effected in the refractive power (spherical and astigmatical) of an intraocular implant of the type having a lens, either formed of a series of laminates of material, or having a lens that is coated with material, said material, when subject to laser energy providing for its expansion or contraction, and thereby varying the curvature of the lens, and hence, effecting an increase or decrease in its relative refractive index or power. The direction at which the laser energy is applied to the lens can effect the relative change in the refractive power of the lens. A modification provides haptics diametrically or concentrically extending from the optic lens, with a segment of material such as hydrogel or collagen at the juncture between the haptics and the lens, which when directionally exposed to laser energy, can cause an increase or decrease in the relative refractive power of the implanted lens.

BACKGROUND OF THE INVENTION

This invention relates to in vivo modification of refractive power of anintraocular lens implant, and more specifically, the invention pertainsto a method of changing the refractive power of an intraocular lens bythe use of laser energy, generally after the lens has been implanted.

It is well accepted that the insertion of an intraocular lens is thebest solution for corrective vision after cataract surgery. Intraocularlenses and methods of inserting them are known to the art. For example,the U.S. Pat. No. 4,056,855, to Kelman, discloses an intraocular lensand a method of implanting same through an incision in the eye. Theassembly includes a lens member and supporting wire initially in adisassembled condition and adapted to be introduced through a smallincision in the eye. U.S. Pat. No. 4,608,049, also to Kelman, disclosesan intraocular lens which may be inserted into the eye through a smallerincision in the cornea. U.S. Pat. No. 4,693,716, to MacKool, disclosesan intraocular lens and implant including a lens centered on a lensaxis. U.S. Pat. No. 4,813,954, to Siepser, discloses a compression,deformation, and dehydration method of fabrication and implantation ofan expanse aisle, hydrogel intraocular lens. The problems associatedwith the foregoing patents include the fact that once the intraocularlens is implanted, it is not possible to change the refractive power ofthe implanted lens. Thus, when further correction becomes necessary,they must be replaced. U.S. Pat. No. 5,041,134, to O'Donnell, theinventor herein, discloses an intraocular lens assembly for implantingin the posterior chamber of a human eye after an extracapusularextraction. The intraocular lens assembly includes an optic holderhaving haptic elements for locating and positioning the optic holder ina fixed position within the posterior chamber of the eye and its opticlens releasably secured to the optic holder for interchange of differentoptic lenses as needed without removing the entire optic holder from theeye. This will allow changing of the refractive index of the implantwithout removal of the entire implant, but still the lens itself must bereplaced. The Schachar U.S. Pat. No. 4,373,281, discloses a variablepower intraocular lens and method of implanting same, the lens includinga fluid expandable sac, which includes the lens portion, and a valveportion, that extends through sclera of the eye so that the fluid issubject to valve action which apparently can change the fluid expandablesac in order to vary the lens refraction. This patent requires the useof an electrode and microprocessor for changing the index of refractionof the intraocular lens to respond to desired parameters, but does nordisclose the use of the laser to make the fine adjustments in therefractive power of the lens.

U.S. Pat. No. 4,669,466, to L'Esperance, discloses a method andapparatus for the analysis and correction of abnormal refractive errorsof the eye. This invention discloses instrumentation for performingrefraction-corrective surgery directly to the cornea. U.S. Pat. No.4,665,913, also to L'Esperance, discloses another related method forophthalmological surgery using a laser, but is limited to use upon theanterior surface of the cornea of the eye and not an intraocular lensimplant. U.S. Pat. No. 4,676,790, to Kern, shows a method of manufactureand implantation of corneal inlays. A laser is used for milling into thesurface of the cornea, to form a recess, so that when the implant isapplied, its surface lies flush with the corneal membrane. Thisinvention does not utilize lasers for changing the index, but simplyprovides lasers for use for inlaying an implant within the cornealsurface.

Another L'Esperance U.S. Pat. No. 4,718,418, discloses another apparatusfor ophthalmological surgery utilizing a laser for contouring thesurface of the cornea to eliminate astigmatism and to provide a cornealcurvature correction.

The U.S. Pat. No. 4,793,344, to Cumming, et al, discloses a method forpreparing corneal donor tissue for refractive eye surgery.

Finally, U.S. Pat. No. 4,923,467, to Thompson, shows an apparatus andprocess for application and adjustable reprofiling of syntheticlenticules for vision correction. This disclosure defines the process ofablating, by laser, a groove in the cornea, to receive the peripheraledge of the implant lens, and then utilizing the laser to deliver areprofiling of the lenticule for refining its refractive power.

None of the aforementioned art utilizes laser energy to change therefractive power of an existing lens of the invention. It is therefore,an object of this invention to provide a method of correction of therefractive power of an implanted intraocular implant by using laserenergy to alter the refractive power of the implanted lens. Both thespherical and astigmatic power could be modified and, multifocalitycould be provided.

Another object of the invention is to provide a method of modifying theimplant power of an intraocular implant by changing the state ofinternal hydration of the intraocular implant.

Yet another object of this invention is to provide a method for changingthe refractive power of an intraocular implant by using laser energy tocollapse the internal layer of the intraocular implant thereby causing areduction in the frontal curvature.

Still a further object of this invention is to provide a method forchanging the refractive power of an intraocular implant by using laserenergy to contract an internal layer of the intraocular implant, therebycausing expansion and the increase of curvature of the implant surface,thereby increasing refractive power.

Still another object of this invention is to provide a method forchanging the refractive power of an intraocular implant by altering thecurvature of the implant by direct surface treatment of the implant withlaser energy.

Another object of the present invention is to provide a method ofchanging the refractive power of the intraocular lens by applying laserenergy to modify the haptic-optic angle of the intraocular implant,thereby causing motion of the optic to either increase or decrease therelative refractive power of the optic.

SUMMARY OF THE INVENTION

Briefly stated, this invention relates to a method of changing therefractive index of a intraocular implant in vivo by applying laserenergy to the intraocular implant so as to open microfenestrations inthe implant, and hence allowing increasing hydration of the internallayer, thereby increasing the front curvature and increasing theirrefractive power. In another embodiment of the present invention, laserenergy is applied to an intraocular implant in vivo to cause thecollapse of an internal layer of the implant thereby causing a reductionof the front curvature. Laser energy is applied to an intraocularimplant to contract an internal layer of the intraocular implant therebycausing expansion and increased curvature of the surface, increasingrefractive power. In another embodiment of the present invention, laserenergy is applied directly to the surface of an intraocular implant,thereby changing the curvature of the implant and thereby increasing ordecreasing the refractive power of the implant. And, in anotherembodiment of the present invention, laser energy is applied to thehaptic optic angle of a intraocular lens assembly, either causingforward motion of the optic, thereby increasing the relative refractivepower, or causing backward motion of the implant causing decrease in therelative refractive power.

This invention contemplates the development of an implant lens which mayhave its refractive index varied even after it has been implanted intothe eye. The variation preferably is done through the use of a laser,which causes an expansion or contraction of select components of thelens, to achieve its index variation. Or, this invention yet recognizesthat the refractive power for the intraocular lens may be varied, evenbefore it is implanted into the eye, so that the changes may be made insito by the ophthalmologist, after determining the extent of correctionrequired to improve the vision of the patient, before the lens implantis made.

The invention utilizes a multicomponent lens, that may be made up ofvarious laminate components, with the front and back layers for the lensbeing formed of a material such as silicone, collagen, polyacrylamide, asoft PMMA, or the like. The center layer for the lens, arrangedintermediately the front and back segments, may be formed of a hydrogel,or other collagen. Thus, it is the change in state of the internalhydration, particularly of the hydrogel component, that causes the lensto vary in shape, and thereby varying the refractive index, to correctfor any error in vision, for the patient. Normally, the purpose of thisinvention is to provide for achieving the correct spherical andcylindrical residual refractive power, after any error has eventuallybecome inherent in the implanted lens, following implant surgery whichmay have taken place at some previous time, in order to reach that powernecessary for the patient to have reasonably clear avoided vision. Inaddition to the foregoing, in order that the hydrogel layer may have agreater effect in achieving the change in curvature of the lens, duringtreatment by the laser, the intermediate layer may have a series ofupstanding integral columns, arranged around the periphery of the frontlayer of the lens, so that the increasing of the hydration of theintermediately arranged layer will increase the front curvature of thelens, thereby increasing its refractive power. These upright columns ofthe hydrogel layer are intended to provide an access for the laserdirectly to the intermediate segment, and these columns function as awaterproof-membrane covered microfenestrations, that allow access to thesaid center layer. Thus, through the use of the laser, a collapse may beattained for the internal layer, which causes a reduction in the frontcurvature, thereby reducing the surface curvature and the refractivepower of the lens. To the contrary, the laser energy may be used tocontract, or heat up, the internal layer B, to cause its expansion, andincrease the curvature of the frontal surface, thereby increasing therefractive power of the lens.

As an alternative, the hydrogel may be located at the junction betweenthe haptic holding the optic lens in place, and when the laser isapplied to the arranged hydrogel, or related material, it causes achange in variation in the haptic-optic angle, thereby effecting achange in the implant power. Thus, applying laser energy to, forexample, the frontal surface of the juncture may cause a forward motionof the optic, causing its increase in relative refractive power.Applying the laser energy to the backside thereof, may cause a backwardmotion to the implant, thereby effecting a decrease in its relativerefractive power. These are examples as to how the optics of theintraocular lens may be varied, to cause a variation and modification inits refractive power, so as to improve the vision of the patient in whomthe lens has been previously implanted, but requires a variation in thesame, either immediately after surgery, so as to fine tune the viewingby the patient through the newly implanted lends, or at some subsequentdate, when a corrective variation in the refractive power of the lensbecomes necessary in order to further improve vision.

Variations in this concept for providing means for varying therefractive power of an intraocular lens, either before the lens isimplanted, or preferably after it has been implanted by the physician,may occur to those skilled in the art upon reviewing the summary of theinvention, in addition to undertaking a study of the description of itspreferred embodiment, in light of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In referring to the drawings, FIG. 1 provides a schematic side viewshowing the laminations for the intraocular lens of this invention;

FIG. 2 is a top plan view thereof;

FIG. 3 is a schematic side view of a modification to the lens of FIG. 1;

FIG. 4 is a schematic side view of the lamination of the lens of FIG. 1;

FIG. 5 discloses a lens with haptics showing a modification in themethod for attaining variation in the refractive power of a lens; and

FIG. 6 is a front view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As previously reviewed, the concept of this invention is to allow usageof a laser device to modify the curvature, either at the front or back,of an optic lens, of the implant type, which may be fabricated frommaterial that is subjected to degrees of hydration, whether the lens beformed totally or partially of a silicone, hydrogel, PMMA, collagen, orthe like. Preferably, the modification can be made after the intraocularlens has been implanted or inserted into the eye.

More specifically, this concept is to provide a way to fine tune therefractive power of the implant in vivo. The laser energy utilized couldbe at any normal and usable wave length such as 1064 nanometer, with thelaser being directed and aimed at the surface, either the front or back,of the implant optic, or at its intermediate lamination, with thepurpose of changing the curvature, and as a result, the refractive powerof the implanted lens. In general, the implant lens might be coated withan inert surface material to facilitate a surface curvature change whenexposed to the effect of the laser. This surface might be enclosed inorder to confine resultant debris. Alternatively, the laser energy couldbe aimed at the haptic-lens implant junction, to alter theanterior-posterior position of the implant, relative to its haptic, andthus change the residual refractive error of the eye. Normally, the moreanterior the location of the optic, the less plus power refractive powervariation or change will be necessary.

Finally, the implant could be used to altar the states of hydration ofthe optic and thus change the shape and hence the refractive power ofthe implant, through laser application.

More specifically, in referring to FIG. 1, a schematic is provided ofthe type of implant lens that may be used in this invention, the lensbeing shown at 1. It may include a series of of laminations, wherein afrontal and curved section of the lens that adds the refractive power toit, is shown at 2, while the posterior lamination 3 may be formed of thesame material. Generally, various types of compositions that may beformed into these frontal and back laminations may include silicone, acollagen, a polyacryalmide, or a soft PMMA, or the like. The essence ofthe invention, though, is to provide a layer of material, generallyintermediately disposed, as can be seen at 4, and which is designed toprovide for an increasing in the hydration of said layer, when exposedto laser energy, whereby the laser may be used to open themicrofenestrations of the material forming this intermediate layer, tothereby increase the front curvature of the lens, and thereby enhancethe refractive power of the implant. This increasing of hydration,through exposure of the intermediate layer to laser energy, enhances itshydration, to thereby force the frontal layer into a greater curvature,to add to the plus power of the refractive index for the constructedlens. As can be further seen, and as shown in FIG. 2, the intermediatelayer 4, which may be formed of a hydrogel or collagen, may haveupwardly extending columns, as at 5, that extend through the anteriorlaminate 2, so as to provide a path for direction of the laser energy,to increase the hydration of the column 5 segments, but also to focusthe laser energy into the hydrogel layer 4, as previously explained.Generally, the columns 5, while formed of the hydrogel or collagen typematerial, which may be subject to increased hydration, when exposedinitially to laser energy, may be lined or covered with awaterproof-membrane, as at 6, so as to focus the laser energy in itsdirection upon the hydrogel material itself making up the laminate B,and its integral columns 5.

As can be seen in FIG. 3, which shows a slight modification to themethod of fabricating the intraocular lens, it includes similar type oflayers making up the laminate of FIG. 1, wherein the anterior andposterior layers 7 and 8, respectively, may be formed of the samecomposition as previously described. The intermediate laminate 9 willlikewise be formed of a layer of material such as hydrogel or collagenthat may have increased hydration when exposed to the initial laserenergy. But, when further exposed to laser energy, such that evaporationof some moisture of the hydrogel layer 9 may be encountered, there maybe a collapse of the layer 9, which causes a reduction in the frontcurvature of the lens, and therefore, the inducement of a lessening ofthe refractive index of the formed lens. This provides a correction inthe focal power of the lens but in an opposite direction. The laserenergy is used to collapse the internal layer, thereby reducing thesurface curvature of the anterior lens 7, and thereby reducing itsrefractive power. When the laser energy is initially used to contact theintermediate layer 9, its energy will heat up this intermediate layer B,causing an expansion and increase in the curvature of the anterior lens7, thereby increasing the refractive power of the implant lens.

FIG. 4 discloses a side view of an anterior lens, similar to that aspreviously reviewed with respect to the lens laminate 2 of FIG. 1, andthe laminate 7 of FIG. 2. The material forming the anterior lens 10 willlikewise be of a silicone, collagen, polyacrylamide, or soft PMMA, orthe like. The impingement of the laser energy directly onto the lens 10attains a focal point at its back surface, approximately at the location11, and may have a tendency to initially heat up and expand the lenslayer 10, to cause an increase in its refractive power, or aftercontinuing exposure of the material to the laser energy, may cause areduction in its moisture content, and a consequential collapse of itsinterior layer, thereby reducing the refractive power of the implantlens. On the other hand, by directing the laser energy onto the frontsurface of the lens 10, this may tend to increase its curavature, andthereby increase its refractive power, or by directing the laser energyonto the back surface of the lens 10, causing a reduction in its frontcurvature, thereby decreasing the refractive power of the intraocularlens. These are examples as to how laser energy may be applied to animplant lens, or various laminates forming it, and which has an effectupon its hydration, to very its shape or curvature, and consequently,its refractive power.

Furthermore, the implant lens may have a special coating upon it, tofacilitate this change of curvature, when exposed to laser energy. Forexample, a PMMA optic coated with silicone, collagen, or hydrogel, mayhave greater susceptibility to hydrate, or dehydrate, when exposed atvarious locations to the laser energy, to thereby change its shape, andhence its refractive power.

It is also likely that the technique of intrastromal or surface lasermodification, as explained in the examples above, could also be appliedto injectable implants, of the type that are used to replace a lens ofthe eye, after a cataract removal. Injectable implants are designed tofill the capsular bag after endocapsular removal of the cataract hasbeen performed through surgery.

A further modification to the subject matter of this invention, wherebythe optic lens may have its refractive index varied, even after it hadbeen previously implanted, can be seen in FIGS. 5 and 6. In thisparticular instance, there may be a material that is formed at thejuncture between the haptic, such as those shown at 12 and 13, and whichconnect to the implant lens 14. At this juncture there may be locatedthe material 15 that may be more readily subjectable to hydration, ordehydration, such as the type of hydrogel or collagen as previouslyexplained. Thus, modifying the haptic-optic angle, through laser energytreatment, provides for an effect in the change in the implant power.Thus, applying laser energy from the front of the lens, as can be seenfrom the direction 16, may have a tendency to cause the optic to moveforwardly, and thereby increase its relative refractive power, as may berequired. On the other hand, applying the thermal laser energy, or lasertreatment, from the rear, as in the direction of the arrow 17, may causea backward motion to the implant, thereby effecting a decrease in itsrelative refractive power, and a lessening of its refractive index, asmay be further required for viewing correction. These are just examplesas to how the optic lens, and its location, or its shape orconfiguration, may be varied by treatment with thermal laser energy, toinherently effect the refractive power of the implanted lens, even at asubsequent date, in order to provide further correction to the patient'sability to view.

Variations or modifications to the subject matter of this invention mayoccur to those skilled in the art upon reviewing the subject matterherein. Such variations or modifications, if within the spirit of thisinvention, are intended to be encompassed within the scope of any claimsto patent protection issuing upon this development. The description ofthe preferred embodiment set forth herein, and its variations, areprovided for illustrative purposes only.

Having thus described the invention what is claimed and desired to besecured by Letters Patent is:
 1. An intraocular lens implant capable ofhaving its refractive power changed, even after the lens has beenformed, including said lens comprising three laminates, said laminatesformed as a front, a back, and an intermediate laminate for the lens, atleast one of the laminates having curvature for providing the refractivepower for correcting viewing through the lens, and at least a second ofsaid laminates formed to provide for a change in the refractive power ofthe lens by being hydrated and dehydrated when exposed to laser energy,the front and the back laminates formed of one of a silicone, collagen,polyacryalmide, and soft PMMA, with the intermediate laminate formed ofone of a hydrogel and collagen, a series of columns extending throughthe front laminate, said columns being formed of the same material asthe intermediate laminate and being formed so as to join with theintermediate laminate.